Researchers monitoring flights in the Northeast found that several cellphone calls are typically made on commercial flights during takeoff or final approach, two critical flight stages when accidents could occur.

The fact that people occasionally cheat, violating FAA and FCC rules, is not a surprise. How often have you seen a flight attendant remind a passenger to turn off their phone or other electronic device?

I have always gone along with the directive, shutting everything down, even though I thought it was probably overblown. The cynic in me assumed that this was a way for the airlines to get you to use the Verizon Airfone in the seatback (or the inflight wi-fi). After all, how could a laptop or PDA bring down a Boeing? And if the electronics are THAT sensitive, wouldn’t there be risk for the duration of the flight, and not just during the climb and descent? But this bit in the article gives pause:

Granger Morgan, head of Carnegie Mellon’s Department of Engineering and Public Policy Department, said the activity recorded shows that the use of electronic devices should be limited on airplanes. Morgan said the disruptions are enough to impact a plane’s navigation or other systems.

Yikes! But how disruptive, exactly? I guess we’ll have to wait for the latest issue of IEEE Spectrum to hit the newsstands.

Our data and the NASA studies suggest to us that there is a clear and present danger: cellphones can render GPS instrument useless for landings.
[...]
In one telling incident, a flight crew stated that a 30-degree navigation error was immediately corrected after a passenger turned off a DVD player and that the error reoccurred when the curious crew asked the passenger to switch the player on again. Game electronics and laptops were the culprits in other reports in which the crew verified in the same way that a particular PED caused erratic navigation indications.